Formaldehyde is emitted from a furniture manufacturing plant at 20 ppm. The process only operates 12 hours per week over 4 different days. The exhaust gas temperature is 25°C. What type of control system would you recommend? You are an engineer for Wood Spec, Inc., a low-cost furniture manufacturer. The owners are planning to significantly expanding their manufacturing facility in a rural area of the Northwest. The U.S. EPA has asked them to estimate the plant expansion effects on local air quality. The plant expansion will process 3 million m2 of particle board (std, UF) daily. You, the engineer, are given the following information based on previous sampling events:

Question

o Exhaust gas temperature from the stack is on average 300 K and exits the stack at 145 m/s.

o Typical meteorological conditions were obtained from a local weather station:

- Strong solar radiation

- Ambient temperature = 299 K

- Wind speed at 10 m = 2 m/s

- Actual lapse rate = -0.015 K/m.

o Both formaldehyde and particulates are a concern. Use emission factors for the most conservative estimate of formaldehyde emissions. Also, assume that 1 mole of formaldehyde reacts in the atmosphere to form 1 mole of ozone.

o The data in Table 5.26 were collected from meteorological stack testing, o Calculate the emission rate of formaldehyde and total particulate matter (PM) in mg/s.



Note: Assume the height of the physical stack is 10 meters



a. What region of the respiratory system is most likely to be affected by each type of PM?

i. Chips

ii. Sawdust

iii. Fine PM

b. What region is least likely to be affected by each type of PM?

c. What is the concentration of formaldehyde in units of PPM in the exhaust stack prior to being emitted into the atmosphere?

d. What is the permissible exposure level (PEL) for formaldehyde?

e. Does this concentration exceed the PEL for workers in the building?

f. How high will the plume rise from the stack in meters?

g. Use Excel to determine the distance in kilometers from the stack will the plume concentration at ground level be greatest (maximum)?

h. What is the maximum predicted ground-level concentration of formaldehyde and total PM assuming these pollutants are reflected?

i. The background concentration of PM is 10 ?g/m3 and ozone is 45 ?g/m3.

Will this location remain in compliance with the United States NAAQS PM and ozone standards based upon the maximum predicted concentration of the pollutants?





What will be an ideal response?

Answer 1

a. Chips – large and not likely to be dispersed downwind

Sawdust – since most of the mass will be found in the larger size particles in the range of 1 to 100 microns, most of the mass of the sawdust will

be deposited in the naseo-pharyngeal region

Fine PM - From Figure 5.22, the remaining fraction is likely to be deposited in the Pulmonary region of the respiratory system



b. Chips & sawdust – the trachio-bronchial region will be least affected

Fine PM – for very fine particles, the nase0-pharyngeal region will be least affected, but for particle closer to 1 micron in size, the trachea-bronchial

region may be less affected.



c. The maximum emission rate of formaldehyde from USEPA AP 42 factors * proposed production rate of the particle board during 3 hours of production time per day:







d. 8?????? ???????????? = 0.75????????????





Thus based upon the concentration exiting the stack, it would appear the maximum formaldehyde concentration within the building would be much higher than the allowable PEL, unless a containment system is used to prevent the formaldehyde form entering the work area.







g. The stability classification will be needed to estimate downwind dispersion. The actual lapse rate was given as:





????????????????????????????? ???????????????????????????????? ???????????????????????????????????????? ????????????? ???? = 2???? ???? ?



????????????????????? ???? ???????????????????????????????????? ???????????????????????????????????????????????????????? from stability tables and description



???????????? ???? ???????????????????? ???????????????? ????????????? ???????????????????????????????????? ???????????????????? ????,???????? ???????????? ???????? ???????????? ???????? ???????????????????????????????????? ???????????????? ????????? ???????????????????????????????????? ???????? ???????????????????? 5.21







h. The maximum concentration is found from:





i. Assuming 1 mole of formaldehyde forms one mole of ozone, then: